The Elliott Core Drills

In connection with a symposium on core drills, it may be of some value tooutline briefly the evolution of the double barrel core drill. The single barrel core drill, or Texas barrel, has been described a numberof times and is undoubtedly merely an evolution of the fishing tool known as abasket. The single barrel drill has served its purpose, its use is decliningand it will not be further discussed in this paper. Jan Koster appears to have been the inventor of the double barrel core drillfor use in loosely consolidated formations. So far as can be learned at thisdate his invention was necessitated by the desire of the Holland GeologicalSurvey to obtain cores in localities where the diamond drill was unsuccessfulby reason of the unconsolidated nature of the formations to be penetrated. Inthe "Memoirs of the Government Institute for the Geological Exploration ofthe Netherlands," W. A. J. M. van Waterschoot van der Gracht says,"this device (the Koster drill) works admirably well in the boring atBaarlo; we succeeded in obtaining a section of many hundred meters of cores, out of sandy clays and scarcely coherent sands." No attempt to introduce the Koster drill into the oil fields of this countrywas made until 1919, when the Shell Co. of California obtained one and testedit in shallow exploration work in an area near what is now the Santa Fe Springsoil fields. The Koster drill appeared to be a step in the right direction, although itsperformance was not satisfactory, due chiefly to inadequate surface equipment.The cores obtained with it were usually short, because the opening to the innerbarrel usually became plugged before the barrel was filled with core. The ShellCo. of California made several changes in the design of the barrel whileoperating in the area mentioned above, and later at Coalinga, but apparentlywithout obtaining complete satisfaction from the drill, as a punch core drillwas used by that company during the intensive drilling campaign at Long Beachin 1921. The original Elliott core drill, as used by the Elliott Core Drilling Co.from 1921 to 1924, was somewhat similar in design to the Koster drill, butadapted to the taking of cores at considerable depth and with several changesmade necessary by California practice in rotary drilling and Californiaformations.